And they agreed it wouldn't be cancelled? Let's see what happens - my understanding is they can't stop the auto cancellation before it happens, so you may have to rely on the staff reinstating the ticket later on. If the auto cancellation had already happened then it's possible that they did reinstate it when you spoke to them.

Bear in mind you will be relying on BA's goodwill to reinstate here, they are not obliged to do so. You may wish to take this in to account when deciding how to approach this with the staff.